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Flash Photolysis of Caged Compounds in the Cilia of Olfactory Sensory Neurons
Published on: October 29, 2011
Olfactory response termination involves Ca2+-ATPase in vertebrate olfactory receptor neuron cilia
Salome Antolin1, Johannes Reisert, Hugh R Matthews
1Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, UK.
The Journal of General Physiology
|March 31, 2010
Summary
Calcium extrusion from olfactory receptor neurons (ORNs) relies more on Ca(2+)-ATPase than Na(+)-Ca(2+) exchange. This finding revises our understanding of olfactory signal termination and calcium homeostasis in ORNs.
Area of Science:
- Neuroscience
- Sensory Biology
- Cell Physiology
Background:
- Olfactory receptor neurons (ORNs) detect odors via a signaling cascade involving cyclic AMP and Ca(2+) influx.
- Termination of the olfactory response requires the removal of intracellular Ca(2+) from cilia.
- A Na(+)-Ca(2+) exchanger has been traditionally considered the primary mechanism for Ca(2+) extrusion in ORNs.
Purpose of the Study:
- To investigate the relative contributions of Na(+)-Ca(2+) exchange and Ca(2+)-ATPase to Ca(2+) extrusion in fire salamander ORNs.
- To elucidate the mechanisms underlying the recovery of the electrical response and intracellular Ca(2+) concentration decay in ORNs.
Main Methods:
- Simultaneous suction pipette recording and Ca(2+)-sensitive dye fluorescence measurements in fire salamander ORNs.
- Manipulating external Na(+) concentration to inhibit Na(+)-Ca(2+) exchange.
- Using vanadate and carboxyeosin to block Ca(2+)-ATPase activity.
Main Results:
- Withdrawal of external Na(+) had a modest effect on the recovery of the electrical response and Ca(2+) decay.
- Blocking Ca(2+)-ATPase with vanadate or carboxyeosin significantly altered response recovery kinetics.
- These findings indicate a substantial role for Ca(2+)-ATPase in Ca(2+) extrusion.
Conclusions:
- Ca(2+)-ATPase plays a significant role in extruding Ca(2+) from ORN cilia.
- Na(+)-Ca(2+) exchange contributes only modestly to Ca(2+) homeostasis in these neurons.
- The study refines the understanding of olfactory signal termination and calcium regulation in ORNs.
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